- A child taking a medication that has a significant drug interaction with iron that cannot be addressed by the timing of administration such as Cholestyramine and Colestipol, Tagamet, Zantac, Pepcid, Axid, ACE inhibitors (captopril, enalapril, and lisinopril), carbidopa, levodopa, levothyroxine, tetracyclines, and quinolones.